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Improving Mindat.orgMagnesiohornblende, Eifel Germany

30th Nov 2010 18:07 UTCOlav Revheim Manager

Amphibole Supergroup

Nickenicher Sattel, Nickenich, Pellenz, Mayen-Koblenz, Rhineland-Palatinate, Germany

According to the information on the locality page Nickenicher Sattel (Eicher Sattel), the photos:

Amphibole Supergroup

Nickenicher Sattel, Nickenich, Pellenz, Mayen-Koblenz, Rhineland-Palatinate, Germany

Amphibole Supergroup

Nickenicher Sattel, Nickenich, Pellenz, Mayen-Koblenz, Rhineland-Palatinate, Germany

in the magnesiohornblende should probably be moved to the amphibole group gallery.

Same probably goes with:

Amphibole Supergroup

Le Novelle Quarry, Ercolano, Mount Somma, Somma-Vesuvius Complex, Naples, Campania, Italy

also labeled magnesiohornblende, but from Monte Somma/Vesuvius in Italy

Olav

30th Nov 2010 20:22 UTCChristof Schäfer Manager

“magnesiohornblende should probably be moved to the amphibole group gallery”

We can do that. For me it is/was more interesting to show, how the “misidentified magnesiohornblende looks like.

Christof

30th Nov 2010 21:38 UTCJeff Weissman Expert

Christof - I have no opinion one way or the other, lets get it right! Unfortunately, almost all of the references listed for the locality are all in German?, which I can't read or access, so I can't check to see if there are any published analysis which could provide a clue. Since you are the only editor of this mineral entry, what was your basis for the "erroneously and without analytical data named Magnesiohornblende" statement - have you analyzed any of these. I photographed the specimen from a reliable source who takes great care in accurate identifications, although mistakes and errors do arise.

Also, there are some identical appearing images of orange prismatic crystals under 'kaersutite' - http://www.mindat.org/gallery.php?min=2129&loc=13795 - one of these has been confirmed , could these "magnesiohornblendes" all be kaersutite? or what is the difference?

thanks

1st Dec 2010 17:46 UTCChristof Schäfer Manager

Jeff,

with less exceptions (Obertiite, rock-forming amphiboles in mantle xenoliths) one cannot find any information about the composition of amphiboles from the Eifel area.

The naming convention, to call the black amphiboles from the Eifel "Ferrohornblende" and the orange-red ones "Magnesiohornblende", has developed between mineral collectors because they "want" individual names for minerals differing in their appearance. As far as I know the literature, till now there is no analytical data published referring to these black and orange-red amphiboles and we have no reference in literature for Magnesiohornblende and Ferrohornblende respectively.

Because of that during the last years various collectors started to get their material probed.

Regarding my samples (red and black ones in the scoria from different localities) the black amphibole turned out to be Kaersutite. The orange-red amphibole has a smaller content of Titanium and is in composition close to the join Kaersutite / (Fluoro)-Magnesiohastingsite.

This information was added to the locality lists.

Christof

1st Dec 2010 18:56 UTCJeff Weissman Expert

Christof - thank you for the clarification and information - I will change my image caption to "amphibole group" but, could it be kaersutite as well?

1st Dec 2010 19:28 UTCChristof Schäfer Manager

Yes, it could be kaersutite.

1st Dec 2010 20:31 UTCJeff Weissman Expert

Without analysis I'll leave it as amphibole, note added to image caption

4th Dec 2010 16:55 UTCUwe Kolitsch Manager

Remained 3 "magnesiohornblende" photos changed to amphibole.

4th Dec 2010 17:03 UTCUwe Kolitsch Manager

Christoph: is the ferrohornblende in http://www.mindat.org/photo-234559.html reliably analysed?

4th Dec 2010 17:07 UTCUwe Kolitsch Manager

Comment added to kaersutite page:

"Note: most kaersutites from the Eifel area (Germany) are probably not reliably identified (i.e., the identification was not based on quantitative chemical analyses and additional diffraction and spectroscopic analyses)."

4th Dec 2010 23:42 UTCChristof Schäfer Manager

Uve,

1. yes, but only quantitative chemical analyses

2. do you have new news regarding these amphiboles ?

some time ago you wrote: “Günter Blass, THE Eifel specialist, kindly asked me to write that these amphiboles are "definitely kaersutite" ".

5th Dec 2010 13:45 UTCUwe Kolitsch Manager

Thanks, Christof (sorry for misspelling your first name).

2. No. I am not aware of any published EMP analyses of the amphiboles in voids. SEM-EDS is not enough for a correct ID, even with modern machines and software.

5th Dec 2010 16:01 UTCChristof Schäfer Manager

The identification of the amphiboles has been done by EMP analyses,

but they are still not published.

I have removed all my entries with unpublished references.

Hope this will help to avoid further misunderstandings.

10th Dec 2010 00:22 UTCEmil Box

After this discussion I have reexamined the analyses, made in October 1995, from orange-brown needles from Eicher Sattel,

Andernach, Germany.

Powder XRD (thanks Thomas Felkel, Currenta, Leverkusen) corresponds with the calculated d-lines from kaersutite at

'mineralienatlas.de'.

ESD (non standardised) also corresponds the best with kaersutite: Na/K=2/ 1; Mg/Fe=8/ 1;Al/Si=1/ 3

Some measered peakheights diverges, without ZAF-correction: (Na,K)/Ca=1.1/ 2; (Mg,Fe)/Ca=4.4/ 2; Ti/Ca=0.8/ 2;

(Si,Al)/Ca=12/ 1

But as non specialist I've heard the low energy-peaks are higher, that would explain the deviation.

Greetings

Milo

10th Dec 2010 14:17 UTCUwe Kolitsch Manager

PXRD and non-standardised SEM-EDS are unfortunately not enough for an unambiguous identification of such amphiboles. But at least the data show that you might have either kaersutite or a closely related amphibole member.

26th Feb 2013 07:34 UTCOlav Revheim Manager

Just out of curiosity, are these now generally accepted as kaersutites?

:)-D

Olav

18th May 2020 09:03 UTCOlav Revheim Manager

Has the orange-brown amphiboles been analysed now? Are their any consesus on their ID?

Thanks

Olav

18th May 2020 11:47 UTCChristof Schäfer Manager

borderline in composition: ferri-kaersutite / oxo-magnesio-hastingsite / magnesio-fluoro-hastingsite

you can find some data in:

The Crystal structure of a fluorine-dominant Titanium Calcium Amphibole from the Eifel ….

Aksenov, Chukanov, May 2016, Zeitschrift für Kristallographie 231(7),

18th May 2020 12:03 UTCOlav Revheim Manager

Christof Schäfer Manager ✉️

The Crystal structure of a fluorine-dominant Titanium Calcium Amphibole from the Eifel

Thanks Christof!

Olav

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